The somewhat open ending of The Vanishing Man (ITV) suggests that last night's comedy thriller was intended as a pilot. One can only hope that it proves more competent than the one played by Neil Morrissey, a man who climbs into his twin-engined plane without a pre-flight inspection, and then stows a set of golf-clubs in the front seat, where they are virtually guaranteed to rearrange his instrument panel at the first quiver of turbulence. He can't even claim ignorance as a mitigating factor: "I was carrying golf clubs on the plane," he says wearily, after being jailed for plutonium smuggling. "The metal sometimes interferes with the compass." His lawyer, stunned by this explanation for a radar-dodging approach back to England, summarises his predicament: "If I don't believe you, how can I make a court believe you?" And if she doesn't believe him, where does that leave us, grappling by now with an armful of improbabilities?

We haven't even got to the bit where he starts to turn see-through after being interfered with by a shadowy scientific organisation known as Gyges. By then, though, our nagging friends the Plausibles have been shown gibbering to the door, and you will either have switched off or settled back to enjoy the special effects. These are rather good, modern computers being far more effective at creating the impression of invisible presence than a length of fishing line with a teacup dangling on the end. Truly pedantic viewers will still find something to niggle at - Morrissey's body, for example, has a conveniently variable index of refraction, sometimes displaying an outline gleam of distortion (when knowing his position in the room will add a little frisson for the audience), at other times offering not the slightest barrier to passing light rays (when a magical levitation will give us more pleasure).

A recent literary version of this storyline handled the matter with something close to rigour (once you'd swallowed the central conceit), noting that until food was digested, it hovered in mid-air as a disgusting cud, and also generating tension from the fact that it is relatively easy for modern technology to detect an invisible man - fluorescent powders, infra- red sights, ultra-sonic beams were all deployed to make things tough for the notionally imperceptible hero. The Vanishing Man is altogether less sophisticated in its treatment, settling instead for the charm of a protagonist who can knock baddies on the head just when they think they have things under control, and then unpredictably reappear in the nude for a bit of comic relief. In its rather innocent glee at such devices and its taste for comic banter, it reminded me most strongly of Randall and Hopkirk Deceased, a bizarre Seventies series in which the detective was assisted by the ghostly presence of his late colleague, who registered his moribund status by wearing a gleaming white suit. If they do make the series, they should schedule it for Saturday tea-time, when its natural audience will be able to enjoy it.

Army of Innocents, BBC1's documentary about National Service, rather threw away a rich and obliquely topical subject. It didn't help that the makers had decided to dramatise the experience of basic training - the reconstructed NCO being, for simple reasons of transmissibility, a mere shadow of the original obscene horror. The sight of an elderly man getting teary-eyed at the memory of kit inspection conveyed the atrocious shock of those first few weeks far more effectively than an actor bellowing mild insults.

Conscription would probably still be educational today - forcing different social types into an instructive intimacy - but back in the Fifties, before television had made us known to ourselves, the experience was frequently nothing short of revelatory; John Peel recalled hearing his first Geordie accent and assuming that the speaker was a Hungarian refugee. Peel joined the slim majority who gave an approving verdict on the experience, but was at pains to distance himself from the simple pieties of the Bring Back brigade. What had he learned from National Service? "Petty theft and evasion," he concluded cheerfully.